Strong light-matter coupling manifested by Rabi splitting has attracted tremendous attention due to its fundamental importance in cavity quantum-electrodynamics research and great potentials in quantum information applications. A prerequisite for practical applications of the strong coupling in future optoelectronic devices is an all-solid-state system exhibiting room-temperature Rabi splitting with active control. Here we realized such a system in heterostructure consisted of monolayer WS and an individual plasmonic gold nanorod. By taking advantages of the small mode volume of the nanorod and large transition dipole moment of the WS exciton, giant Rabi splitting energies of 91-133 meV can be achieved at ambient conditions, which only involve a small number of excitons. The strong light-matter coupling can be dynamically tuned either by electrostatic gating or temperature scanning. These findings can pave the way toward active nanophotonic devices operating at room temperature.

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Electrically insulating boron nitride (BN) nanosheets possess thermal conductivity similar to and thermal and chemical stabilities superior to those of electrically conductive graphenes. Currently the production and application of BN nanosheets are rather limited due to the complexity of the BN binary compound growth, as opposed to massive graphene production. Here we have developed the original strategy "biomass-directed on-site synthesis" toward mass production of high-crystal-quality BN nanosheets. The strikingly effective, reliable, and high-throughput (dozens of grams) synthesis is directed by diverse biomass sources through the carbothermal reduction of gaseous boron oxide species. The produced BN nanosheets are single crystalline, laterally large, and atomically thin. Additionally, they assemble themselves into the same macroscopic shapes peculiar to original biomasses. The nanosheets are further utilized for making thermoconductive and electrically insulating epoxy/BN composites with a 14-fold increase in thermal conductivity, which are envisaged to be particularly valuable for future high-performance electronic packaging materials.

Elemental boron arouses great interest from both scientific and technological areas of research because it has unique chemical and physical properties and its theoretical tubular structures may have higher electrical conductivity than carbon nanotubes. [1][2][3][4][5][6][7] High conductivity and chemical stability of boron or boride nanostructures have made it an attractive candidate for future applications in ideal cold-cathode materials, high-temperature semiconductor devices, or fieldeffect transistors. [8][9][10][11][12][13][14] In particular, for the application of field emission (FE), it is especially useful to synthesize large, vertical arrays of boron nanowires (BNWs) with the desired surface work function and FE behavior. So far, to our knowledge, while both amorphous [15][16][17][18][19][20] and crystalline boron nanowires [21,22] have been fabricated by magnetron sputtering, laser ablation, or chemical vapor methods, vertical arrays of single-crystal boron nanowires over a large area have not been synthesized in a one-step process. In addition, little attention [23][24][25] has been paid to the measurements of the physical properties of an individual boron nanowire. In this Communication, we report the successful synthesis of high-density, vertically aligned single-crystal boron nanowire arrays with a nanowire diameter of approximately 20-40 nm by a thermal carbon-reduction method. Moreover, we have measured the FE behavior and surface work function of a single boron nanowire, which is critical to evaluate the possibility of using boron nanowires as field-emission materials. For the purpose of better understanding the field-emission mechanism of a boron nanowire, the field-emission properties of a BNW film are also measured to compare with those of an individual nanowire. Figure 1 shows large-scale boron nanowire arrays on a Si(001) substrate after approximately 2-4 h of growth. As shown in Figure 1A, the high-density arrays are aligned vertically on the silicon substrate. Figure 1B is the highresolution scanning electron microscopy (SEM) image of the aligned BNWs, in which one can see that the length of the BNW is about 5 mm and the morphology of the nanowires is uniform. The aspect ratio of each boron nanowire is about 200, which is high enough for a field-emission application. The side and top views of the boron nanowire are shown in Figure 1C and D, respectively, which reveals the detailed morphology of the BNWs. The boron nanowires have a diameter of about 20-40 nm and no catalyst is found at their tip. The catalysts, however, were found to lie on the substrate arbitrarily when we peeled off some nanowire film from the substrate, as shown in Figure 1C. Thus, we believe that the growth is through a vapor-liquid-solid (VLS) mechanism and the binding force between the Fe 3 O 4 catalyst and the silicon substrate is strong. This strong binding leads to good conductivity between the boron nanowires and the substrate, which may contribute to their good field-emission properties. The alignment of BNWs can...

Single crystalline boron nanocones are obtained by a simple chemical vapor deposition method. Electric conductivity values of boron nanocones are (1.0–7.3) × 10–5 (Ω cm)–1. Results of field emission show the low turn‐on and threshold electric fields of about 3.5 V μm–1 and 5.3 V μm–1, respectively. Boron nanocones with good electrical transport and field emission properties are promising candidates for application in flat panel displays and nanoelectronics building blocks.